This longitudinal study examined bidirectional associations between special education pupils' teacher-child relationship characteristics (quality, satisfaction, and conflict), classroom structure, and behavioral problems (externalizing and attention-hyperactivity). A secondary goal was to investigate the extent to which severity of behavioral problems moderated the prospective associations. Participants were 586 pupils (86% boys) in Grades 4 to 6 (M[subscript age time 1] = 10.82 years, SD = 0.86) from 13 special education schools in the Netherlands and their teachers. Findings indicated that primarily teacher-child conflict was related to increased externalizing problems. More classroom structure was related to decreased attention-hyperactivity problems, but higher teacher-child relationship quality was linked to increases in attention-hyperactivity problems. Moreover, both types of problems were related to increases in conflict. Severity of behavior problems did not moderate these associations. Although findings were not consistent in both school years, they suggested that particularly reducing conflict and instilling more classroom structure were the most effective strategies in reducing behavioral problems. Furthermore, disrupting negative transactional associations between conflict and externalizing behavior is important to reduce externalizing behavior.